CN109211631B - A method for measuring reflow performance of iron-bearing charge - Google Patents

Abstract

The invention relates to the technical field of blast furnace ironmaking, and provides a method for characterizing the reflow performance of an iron-containing charge. The method grinds the iron-containing charge into a sample, and when the sample is prepared, the iron-containing charge and coke are ground to a particle size < 147μm, respectively made a cylindrical sample and a gasket sample on a high-pressure tablet press, the amount of coke is 0~30% of the total mass of the sample; the linear displacement of the sample after the maximum expansion of the sample in the reduction reaction melting experiment is relative The degree of change is used as a characteristic quantity to characterize the reflow performance of the iron-containing charge. The method of the invention uses the reduction reaction melting test to measure the reflow performance of the iron-containing charge, and the reflow performance of the blast furnace charge structure during the reduction reaction is a very important factor affecting the characteristics of the reflow zone; the reduction reaction melting test can be used to simulate the iron-containing charge. The main characteristics of the reflow zone in the blast furnace; the use of the method of the present invention can partially replace the traditional high-temperature droplet test; the method is simple, reasonable and has broad application prospects.

Description

A method for measuring reflow performance of iron-bearing charge

technical field

The invention relates to the technical field of blast furnace ironmaking, in particular to a method for measuring the reflow performance of iron-containing charge.

Background technique

In the process of ironmaking, it is necessary to study the high temperature droplet characteristics of different charge structures to ensure the stable and forward running of the blast furnace. Under the condition that the coke strength and the particle size of the incoming iron-containing charge remain unchanged, the air permeability of the material column in the blast furnace depends on the shape of the reflow zone and the reflow performance of the incoming iron-containing charge. The width and height of the blast furnace reflow zone have a great influence on the permeability of the blast furnace and the forward run of the blast furnace.

The current method for determining the reflow performance of iron-containing charge is mainly determined by the droplet test, and is characterized by parameters such as pressure difference, load reflow temperature, and characteristic value S. The droplet test uses a reducing gas of N ₂ :CO=70:30, and the added coke will also directly participate in the reaction in the high temperature region. The reduction reaction in the droplet process includes direct reduction and indirect reduction. In the droplet test, in order to make the molten material drop as soon as possible, a load should be added to the sample, and the test is called a load softening test. The samples used in the droplet test are all raw materials from the production site, rather than chemical reagents with uniform composition. The volume of different droplet equipment is also different, and the volume of the equipment has a trend of large development. At present, there is no national standard for the high-temperature droplet test, only the method commonly used in the industry.

The experimental period of the melting drop test is long, time-consuming, and labor costs are high.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the deficiencies of the prior art, provide a method for characterizing the reflow performance of iron-containing charge, utilize reduction reaction melting test to measure the reflow performance of iron-containing charge, and the reflow performance of blast furnace charge structure during reduction reaction It is a very important factor affecting the characteristics of the reflow zone; the reduction reaction melting test can simulate the main characteristics of the iron-containing charge in the blast furnace reflow zone; the method of the invention can partially replace the traditional high-temperature droplet test.

The technical scheme of the present invention is as follows:

A method for measuring the reflow performance of iron-containing charge, the method is to grind the iron-containing charge to make a sample; use the relative change degree of linear displacement after the maximum expansion of the sample during the reduction reaction melting experiment as a characteristic quantity to measure the content Reflow properties of iron charge.

Further, the characteristic quantity is the melting parameter RH _F , and the calculation formula is as follows:

RH _F =ΔT/T ₁ ×ΔH×100 (1)

Among them: T ₁ is the melting shrinkage start temperature, T ₂ is the reflow end temperature, the temperature interval ΔT=T ₂ -T ₁ , and H ₁ is the shrinkage height of the sample column when the reflow process reaches the maximum shrinkage for the first time. ), H ₂ is the expansion height from the first maximum contraction to the maximum expansion after melting, the displacement change rate ΔH is the displacement change rate when the sample column produces the maximum expansion during the reaction process, ΔH=H ₂ /H ₁ .

和垫片试样，直径24mm×4mm；焦炭量为试样总质量的0～30％。对于不同的矿种，如烧结矿、球团矿、块矿等，所需配入焦炭的含量按照矿种的不同在该范围内予以调整。Further, when preparing samples, the iron-containing charge and coke were ground to a particle size of <147 μm, and cylindrical samples were made on a high-pressure tablet press.

And gasket sample, diameter 24mm × 4mm; coke amount is 0-30% of the total mass of the sample. For different types of minerals, such as sintered ore, pellets, lump ore, etc., the content of coke to be added should be adjusted within this range according to the different types of minerals.

Further, different iron-containing charges are respectively subjected to reduction reaction melting tests to obtain the melting parameter _RHF , and a database of melting parameters _RHF under different ratios of various iron-containing charges is formed; Corresponding relationship of melting properties;

The proportioning structure of the iron-containing charge in the blast furnace ironmaking process is adjusted according to the database, so as to improve the high-temperature droplet characteristics of the iron-containing charge.

Further, the iron-containing charge includes a single ore of natural iron ore nuggets, sintered ore, and pellets, or a mixed ore of natural iron ore nuggets, sintered ore, and pellets.

Further, the test device used in the method includes: a high-temperature furnace, a sample table, a slideway system for pushing the sample table, a temperature measurement system, a camera and recording system, an air supply system, and an information processing device;

The slideway system sends the sample table into or out of the high temperature furnace, the gas supply system supplies the high temperature furnace, and the thermocouple provides the heat source for the high temperature furnace. The information processing device; the temperature measurement system inputs the temperature information into the information processing device through the signal converter.

Further, the high temperature furnace is a visible horizontal high temperature furnace, and its rated power is 8kw.

The beneficial effects of the present invention are:

(1) The test process is visible and can be recorded in real time, and the test equipment is much simpler than the droplet test equipment, and the cost and manpower of spare parts and tests are also low, which achieves the purpose of greatly reducing the detection cost; the cost of the test equipment is about 1/3 of the test, the use cost and labor cost are greatly reduced compared with the melting drop test.

(2) The phenomenon of the test process can be monitored at any time, and the difference in the melting characteristics of different iron-containing charges when they are reacted can be found in time;

(3) The test period is short, which can quickly analyze the melting characteristics of the reduction reaction of various single iron-containing materials and different blast furnace charge structures, meet the technical analysis needs of the blast furnace for frequent changes of new materials and rapid adjustment of the charge structure, and provide necessary guidance for blast furnace production. basis;

(4) The melting characteristic test when there is a reduction reaction can provide necessary information for the load drop test, and the two test results complement each other and provide more information for the adjustment of the blast furnace charge structure;

(5) It can partially replace the traditional high temperature droplet test;

(6) The method is simple, reasonable and has broad application prospects.

Description of drawings

FIG. 1 is a schematic structural diagram of a test device in an embodiment of the present invention.

Figure 2 shows a schematic diagram of the melting process of the Roy Hill block sample during the reduction reaction.

Figure 3 is a schematic diagram of the melting process of a single iron-containing charge sample during the reduction reaction;

Among them: Figure 3(a) is the Australian ore block, Figure 3(b) is the Atlas block, Figure 3(c) is the sinter 1, Figure 3(d) is the sinter 2, and Figure 3(e) is the Sinter 3, Fig. 3(f) is sinter 4, Fig. 3(g) is Longhui titanium ball ore, and Fig. 3(h) is Longhui ball ore.

Figure 4 is a schematic diagram of the melting process of the mixed ore of the two charge structures during the reduction reaction;

Among them: Fig. 4(a) is the charge structure 1, and Fig. 4(b) is the charge structure 2.

Figure 5 is a schematic diagram of the melting process of the mixed ore containing high basicity sintered ore during the reduction reaction;

Among them: Fig. 5(a) is the mixed charge structure 3, and Fig. 5(b) is the mixed charge structure 4.

Figure 6 shows a schematic diagram of the visual reflow process of the reduction reaction of the Atlas block replacing other charges:

Among them: Fig. 6(a) is the mixed ore corresponding to scheme 1, Fig. 6(b) is the mixed ore corresponding to scheme 2, Fig. 6(c) is the mixed ore corresponding to scheme 3, and Fig. 6(d) is corresponding to scheme 4 of mixed mines.

Figure 7 is a schematic diagram showing the comparison between the characteristic number of molten droplets and the reactive melting parameters of a single charge (lump and pellet).

Fig. 8 is a schematic diagram showing the comparison between the characteristic number of droplets of a single charge (sinter) and the reaction melting parameters.

Figure 9 shows the comparison of the characterization parameters of the two reflow performance test methods for the mixed charge.

Detailed ways

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered isolated, and they can be combined with each other to achieve better technical effects. In the drawings of the following embodiments, the same reference numerals appearing in the various drawings represent the same features or components, which may be used in different embodiments.

Compared with the traditional high-temperature droplet test and the characteristic value _S , the present invention measures the soft melting performance of the iron-containing charge through a new test method and melting parameter RHF.

The test equipment used in the embodiment of the present invention includes: a visual horizontal high-temperature furnace (rated power is 8kw), a slideway system for pushing the sample, a temperature measurement system, a camera and recording system, and a gas supply system, etc. method to study the melting process of iron-containing charge during high temperature reduction. The test equipment is shown in Figure 1. The gas supply system supplies gas (CO+N ₂ ) to the high-temperature furnace, the thermocouple provides the heat source for the high-temperature furnace, and the camera or video camera captures the changing state of the sample during the test, and transmits the picture information to the Computer (information processing device); the temperature measurement system inputs temperature information into the computer (information processing device) through a signal converter.

试样和垫片试样，直径24mm×4mm。试验配入适合的焦炭量(0～30％)，对于不同的矿种，如烧结矿、球团矿、块矿等，所需配入焦炭的含量按照矿种的不同根据实际或经验在该范围内进行调整。其目的是要在试验过程中保持一定的还原气氛，研究有还原反应时的熔化特性。在熔化后的试样表面上分布一些被还原的铁颗粒，反应过程中有直接还原发生，但也有没有被完全还原的铁氧化物(这与含碳球团内配高碳量，将铁氧化物全部还原出铁，并在高温下形成渣铁分离是完全不同的)。The test process is as follows: grind the iron-containing charge and coke to a particle size of <147 μm, and make cylindrical samples on a high-pressure tablet press.

Sample and gasket sample, diameter 24mm × 4mm. The appropriate amount of coke (0-30%) is added in the test. For different minerals, such as sinter, pellets, lump ore, etc., the content of coke that needs to be added depends on the actual or experience of different minerals. adjustment within the range. The purpose is to maintain a certain reducing atmosphere during the test, and to study the melting characteristics when there is a reduction reaction. Some reduced iron particles are distributed on the surface of the melted sample, and direct reduction occurs during the reaction, but there are also iron oxides that are not completely reduced (this is related to the high carbon content in the carbon-containing pellets, which oxidizes the iron It is completely different from the reduction of iron and the formation of slag and iron separation at high temperature).

During the reduction reaction, the shape of the iron-containing charge sample during the melting process will occur: the characteristics of shrinkage first, expansion later, and shrinkage again. This is due to the gas escape from the reduction reaction in the sample. In the blast furnace, the reduction volume expansion rate of the iron-containing charge and the duration of the reduction reaction directly affect the permeability and thickness of the soft-melt zone, and the temperature at which the reduction and melting of the iron-containing charge begins will affect the position of the soft-melt zone.

_The relative change degree of the linear displacement after the maximum expansion of the sample is used as the characteristic quantity to characterize the melting characteristics _of the reduction reaction. The displacement change rate ΔH is the displacement change rate when the sample column produces the maximum expansion during the reaction process.

The melting parameter RH _F is defined to characterize the reduction reaction, and its calculation formula is as follows:

RH _F =ΔT/T ₁ ×ΔH×100 (1)

Among them: T ₁ is the starting temperature of melting shrinkage (the temperature corresponding to Fig. 2a), T ₂ is the end temperature of reflow (the temperature corresponding to Fig. 2d), the temperature interval ΔT=T ₂ -T ₁ , and H ₁ is the first reflow process. The shrinkage height of the sample column when the maximum shrinkage is reached for the first time (Fig. 2b), _H2 is the expansion height from the first maximum shrinkage to the maximum expansion after melting (Fig. 2c), and the displacement change rate ΔH is the reaction process sample The rate of change in displacement when the column produces maximum expansion, ΔH=H ₂ /H ₁ .

In the melting parameter _RHF , the smaller the melting temperature range corresponds to the narrower melting zone thickness, the higher the melting onset temperature, the lower the position of the soft melting zone, and the low displacement change rate has little effect on the permeability. The smaller the melting parameter RH _F , the smaller the effect of the charge on the gas permeability during the reaction melting process.

In the following examples, the commonly used iron-containing charges for a blast furnace in a factory were selected including: Roy Hill block, Atlas block, Ao block, sinter 1 to sinter 4, Longhui titanium pellets, Longhui pellets, Its chemical composition is shown in Table 1.

Table 1 Chemical composition of blast furnace iron-containing material used in reduction reaction test

Table 2 presents a sample scheme for the melting characteristics of different iron-containing charges during the reduction reaction.

Table 2 Experimental scheme of melting characteristics during reduction reaction

Figure 2 shows the melting process of the Roy Hill block sample in the presence of a reduction reaction.

Figure 3 is a schematic diagram of the melting process during the reduction reaction of Australian lumps, Atlas, sinter and pellets.

Table 3 gives the melting characteristic parameters of a single charge.

Table 3 Melting characteristic parameters of a single charge during reduction reaction

Following the method used by a company to maintain the life of the blast furnace hearth and hearth, titanium-containing pellets have been used in production to protect the hearth and hearth. During production, the amount of titanium-containing pellets added should be adjusted accordingly according to the temperature changes of the hearth and the bottom of the furnace. Table 4 shows the blast furnace charge structure of two different pellets fed into the blast furnace during normal production of an enterprise.

Table 4 Blast furnace charge structure during normal production

Table 5 shows the test scheme of the reflow performance of the two different pellets in the blast furnace during normal production during the reduction reaction.

Table 5 Test scheme of reflow performance of two different charge structures of blast furnace during reduction reaction

Figure 4 shows a schematic diagram of the melting process of the mixed ore with two charge structures during the reduction reaction.

Table 6 gives the melting characteristic parameters of the mixtures of the two charge structures.

The melting characteristic parameters of the mixture of the two charge structures during the reduction reaction in Table 6

The experimental protocol for the melting characteristics during reduction of mixed charges containing sinter with different basicities (basicity of 2.53 and 2.31, respectively) is as follows.

Table 7 shows the two kinds of charge structures containing high basicity sinter in the blast furnace test of an enterprise.

Table 7 Blast furnace charge structure/% containing high basicity sinter

Table 8 shows the test scheme for the reduction reaction reflow performance of the blast furnace mixed charge during normal production.

Table 8 Test scheme of melting characteristics of mixture containing high basicity sinter during reduction reaction

Figure 5 is a schematic diagram of the melting process of the mixture containing high basicity sintered ore during the reduction reaction.

From the test results in Figure 5, the melting characteristic parameters of sintered ore with different basicity are given in Table 9.

Table 9 Melting characteristic parameters of mixed ore containing high basicity sinter during reduction reaction

It can be seen from Table 9 that the melting parameter RH _F of the sinter mixture with basicity of 2.53 reaches 16.68, which is much higher than the melting parameter of sintered ore mixture with basicity of 2.31, _RHF 7.22, mainly due to the high displacement rate. To. Although the melting parameter of the mixed charge with ultra-high basicity is lower than the melting parameter _RHF value of the single ultra-high basicity sinter (see Table 3), the increase is still too large, so the sintering of ultra-high basicity Mine will adversely affect permeability production in blast furnaces.

Table 10 below shows the mixed iron ore scheme using Atlas nuggets instead of Australian nuggets, and the reduction experiment of iron-bearing nuggets is carried out, see Table 11.

Table 10 Experimental scheme of charge structure using Atlas block instead of Australian block and pellets/%

Table 11 Test scheme of reflow performance of mixed charge in blast furnace with different schemes during reduction reaction

According to the scheme in Table 11, the experiment of replacing the Australian ore block with Atlas block was carried out. Figure 5 shows the reduction reaction to visualize the reflow process.

It can be seen from Fig. 5 that when the proportion of Atlas block is increased to 15% (scheme 4), the volume expansion of the sample during reductive melting is higher than that of other schemes.

Table 12 shows the reduction reaction melting characteristic parameter RH _F of increasing the proportion of Atlas block to replace other charge.

Table 12 The reduction reaction melting characteristics of the mixed charge with increasing the proportion of Atlas lump ore

It can be seen from Table 12 that with the gradual increase of the proportion of Atlas blocks, the melting parameter _RHF of the reduction reaction increases continuously, which is caused by the increase of the displacement change rate. It is consistent with the increase in the volume expansion of the sample in the proportion of the Atlas block in Figure 6, that is, the increase in the intensity of the reaction process.

As a traditional method to test the reflow performance of blast furnace charge structure, the droplet test uses a certain load and reducing gas to simulate the actual state of the blast furnace reflow zone, and the characteristic value S of the droplet is used as the key to characterize its characteristics. One of the parameters has been agreed by domestic iron-making workers. The position, thickness and air permeability of the blast furnace reflow zone affect the distribution of gas flow in the blast furnace, and the reaction melting parameters of the charge during the reduction reaction also directly affect the characteristics of the reflow zone. According to the single charge and various charge structures used in a blast furnace of an enterprise, the correlation between the characteristic value of the droplet (S) and the reactive melting parameter (RH _F ) was explored.

Table 13 gives the characteristic values of the droplets and their reaction melting parameters for a single iron-containing charge.

Table 13 Droplet eigenvalues and reaction melting parameters of a single iron-bearing charge

It can be seen from Table 13 that the droplet characteristic value of sintered ore is much higher than that of other single iron-containing charge, and the value of the droplet characteristic value of sinter 2 is too large. , the other values are too small, and its regular characteristics cannot be observed intuitively. So, plot it separately to determine its correlation.

Figures 7 and 8 are the comparison diagrams of the characteristic values of the droplets in the droplet test of a single iron-bearing charge (lumps and pellets) and a single iron-bearing charge (sinter) and the reaction melting parameters during reduction reaction melting, respectively.

It can be seen from Fig. 7 that the characteristic numbers of molten droplets of natural iron ore nuggets and titanium-containing pellets are respectively related to the change rules of their respective reaction melting parameters, and each has a good consistency. For example, the natural iron ore blocks are all Roy Hill block > Atlas block > Australia block, and the magnitudes of the changes of the two parameters are also very similar. The change trend and magnitude of the two pellets are basically the same.

In Fig. 8, the change rules of the characteristic values of the droplets and the reaction melting parameters of the sinter with different basicities are basically the same, sinter 2> sinter 3> sinter 4 and sinter 1. Since the basicity of sinter 4 and sinter 1 are not much different, they are 2.05 and 2.00 respectively, the characteristic values of molten droplets are 114 and 91 respectively, and the reaction melting parameters are 4.84 and 6.30, respectively, it can be considered that the difference between the two is relatively small. fluctuate within the range. For sinter it can also be considered that the magnitude of the variation of the two parameters is very similar.

Since the reaction melting parameters only reflect the melting characteristics of the charge in the reduction reaction, the load melting droplet experiment also includes factors such as load and pressure. Therefore, the reaction melting parameters and the characteristic values of the molten droplets have the same variation rule and similar amplitude in a single charge of the same variety, but the variation amplitudes of the single charge of different varieties are quite different, which is related to the composition of the main oxides in the single charge.

All in all, the characteristic number of molten droplets and the reaction melting parameters of the same type of single iron-containing charge have good consistency in characterizing the reflow characteristics of the charge in the blast furnace.

Table 14 shows the characteristic number of molten droplets and reaction melting parameters of the blast furnace mixed charge in an enterprise

Table 14 Droplet characteristic number and reaction melting parameters of mixed charge

Figure 9 shows the comparison between the characteristic number of molten droplets and the reaction melting parameters of a blast furnace mixed charge in an enterprise.

It can be seen from Table 14 that for the mixed charge corresponding to charge structure 1 and charge structure 2 used in the blast furnace production of a certain enterprise, the reduction reaction melting parameter increased from 4.18 to 6.67, and the characteristic value of the droplet increased from 229KPa·°C to 258KPa·°C. For Schemes 1 to 4, as the proportion of using Atlas ore to replace Australian ore gradually increases, the reduction reaction melting parameter gradually increases from 11.20 to 14.18, 15.73 and 19.96, and the number of droplet eigenvalues also gradually increases from 289KPa·℃ to 395KPa·℃, 403KPa·℃ and 427KPa·℃.

It can be seen from the above that the characteristic number of molten droplets and the reaction melting parameters of the mixed charge with different charge structures not only change in the same law, but also in the same variation range. The characteristic number of molten droplets of mixed iron-containing charge in blast furnace has a good correlation with reaction melting, which is not related to the type and proportion of oxides in different charge structures of blast furnace.

Through the above comparative test, it can be concluded that the traditional load drop test method for optimizing the blast furnace charge structure and the reduction reaction melting characteristics used in this application are in characterizing the natural iron ore nuggets, sinter and pellets of a single iron-containing charge. , the characterization of a single type of iron-containing charge and the load drop test has a good consistency; the characterization of the mixed iron-containing charge used in the blast furnace of this enterprise has a good consistency.

In practical applications, different iron-containing charges are respectively subjected to reduction reaction melting tests and the melting parameters _RHF are obtained to form a database of melting parameters _RHF under different ratios of various iron-containing charges; establish different ratios of iron-containing charges Corresponding relationship with reflow performance; adjust the proportioning structure of iron-containing charge in the blast furnace ironmaking process according to the database, thereby improving the high-temperature droplet characteristics of the iron-containing charge.

Although several embodiments of the present invention have been presented herein, those skilled in the art should understand that changes may be made to the embodiments herein without departing from the spirit of the present invention. The above-mentioned embodiments are only exemplary, and the embodiments herein should not be construed as limiting the scope of the rights of the present invention.

Claims (6)

1. The method for measuring the reflow property of the iron-containing furnace burden is characterized in that the iron-containing furnace burden is ground into a sample; determining the reflow property of the iron-containing furnace charge by using the relative change degree of linear displacement after the maximum expansion amount of the sample in the reduction reaction melting experiment as a characteristic quantity;

the characteristic quantity is a melting parameter RH_FThe calculation formula is as follows:

RH_F＝ΔT/T₁×ΔH×100 (1)

wherein: t is₁For melting shrinkage onset temperature, T₂The temperature interval delta T is T as the end temperature of the reflow₂-T₁，H₁The shrinkage height H of the sample material column when the maximum shrinkage is reached for the first time in the reflow process₂The displacement change rate is the displacement change rate when the sample material column generates maximum expansion in the reaction process, and is delta H ═ H₂/H₁。

2. The method of claim 1, wherein the iron-containing charge and coke are ground to particle size to prepare the sample<147 μm, respectively making into cylindrical samples on a high-pressure tabletting machine

And a gasket sample with the diameter of 24mm × 4mm, wherein the coke content is 0-30% of the total mass of the sample.

3. The method of claim 1 or 2,

respectively carrying out reduction reaction melting tests on different iron-containing furnace materials and obtaining melting parameters RH_FForming the melting parameter RH of various iron-containing furnace charges in different proportions_FA database of (a); establishing corresponding relations between different proportions of iron-containing furnace burden and the reflow property;

and adjusting the proportioning structure of the iron-containing furnace burden in the blast furnace ironmaking process according to the database, thereby improving the high-temperature molten drop characteristic of the iron-containing furnace burden.

4. The method of claim 1 or 2, wherein the iron-containing charge comprises a single ore of natural iron ore blocks, sinter ore, pellets, or a mixture of natural iron ore blocks, sinter ore, pellets.

5. A method according to claim 1 or 2, wherein the method employs a test device comprising: the device comprises a high-temperature furnace, a sample table, a slide system for pushing the sample table, a temperature measuring system, a camera shooting and recording system, an air supply system and an information processing device;

the slide system sends the sample platform into or out of the high-temperature furnace, the gas supply system supplies gas for the high-temperature furnace, the thermocouple provides a heat source for the high-temperature furnace, the camera or the video camera shoots the change state of the sample in the test process, and the picture information is transmitted to the information processing device; the temperature measuring system inputs the temperature information into the information processing device through the signal converter.

6. The method of claim 5, wherein the furnace is a visual horizontal furnace rated at 8 kw.

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